Lead Acid circulatory air pump

[solarman216]

Hi all I need a pump to circulate gas from the top of my batteries to the bottom in order to eliminate acid stratification during charging in order to shorten the charge time and lower the temperature, I have 12 x 2 volt cells about 600 mm deep, currently I need to over charge in order to promote gassing to adequately mix the electrolyte, a pump would reduce this by 20 to 30% so could be well worth it if I can find a pump to do the job, thinking along the lines of aquarium air pumps but know nothing about them, looked at battery guys but prices are stupid, thing is the air in needs to be from the cells and not from fresh, any ideas? Rick

[Lazy-Ferret]

Not sure I understand, does this mean you will basically pit a tube in the cell to the bottom, and then blow air in?

I know it's not exactly the same, but when I used to etch the PCB's at the university, we used a fish tank air pump to circulate the ferric chloride.

How much air will you need?

[jims-terrano]

One thing that struck me is what about sparks from a pump if recirculating the charging gases.

Advantage of an aquarium pump is they are electromagnetic that operate a diaphragm which should eliminate any risk of sparks.

Biggest problem would be feeding the gases into the pump and would the pump actually circulate enough volume.

What about a 12v tyre inflator as I think they tend to be a piston type compressor.

[Lazy-Ferret]

Most fish tank don't spark, they use a pair of electrical coils, to pull a solenoid connected to a pair of bellows back and forward. Main problem is, the bellows tend to work harden, and you have to replace them every year or so.

What you ideally want is one of the old Medcalf Hy-Flo pumps, beautiful bit of kit, they use a coil to induce an eddy current into an aluminium disk, that then revolves, and drives 2 crank shafts connected to little pistons.... all you have to do is put a drip of oil on them once a month or so. Only problem is, they fetch quite good money now, as they are collectors items. I had 2 for my fish tanks, spent almost as much time watching the pumps, as watching the fish... Other thing is, rather than the annoying buzzing the modern ones make, these do a relaxing chuff...

[solarman216]

Originally Posted by Lazy-Ferret

Not sure I understand, does this mean you will basically pit a tube in the cell to the bottom, and then blow air in?

I know it's not exactly the same, but when I used to etch the PCB's at the university, we used a fish tank air pump to circulate the ferric chloride.

How much air will you need?

Not much air just enough to produce bubbles to stir the acid up, from what I have seen of fish tanks I might need a separate pump for each cell, plus it may be important to keep the gasses for each cell separate, Rick

[Lazy-Ferret]

Originally Posted by solarman216

Not much air just enough to produce bubbles to stir the acid up, from what I have seen of fish tanks I might need a separate pump for each cell, plus it may be important to keep the gasses for each cell separate, Rick

The main problem is, I can't think of any pumps that allow you to choose where the "in" air comes from. I forgot that when I mentioned the Medcalf one, as the pistons are made from brass, and I think the acid air would attack the piston. I guess it would have to be one with the Rubber bellows, and these can be got in a multitude of sizes.

Most of the pumps I have had over the years have an opening on the side or back about 1/2" across, with a foam filter pushed it, you would be able to make a converter that pushed into there fairly easily.

Does the drawn air from a battery have to be returned to the same battery, because if it does, then as you say, you would need a pump for each cell?

If not, then I think you would be fine for a larger fish tank pump to do 2 or 3 cells, especially if you fitted an air stone to each one. The only problem with the airstones is in water, over time they block up, and again, I am not sure what the acidic air would do to them.

[rayf3262]

A peristaltic pump like this may do?

https://www.amazon.co.uk/Yosoo-Peris...=fsclp_pl_dp_1

Here's how it operates:
https://en.m.wikipedia.org/wiki/Peristaltic_pump

[solarman216]

Thanks Ray, they look the business, not sure if I need one for each cell but guess I do to keep the acid contained to each, so 18 x 12 = 216 plus pipe and bits, dear but could be worth it in the long run, Rick

[rayf3262]

Ive seen some on eBay for under a fiver.

[rayf3262]

Here...
https://www.ebay.co.uk/itm/DC12V-24V...xY-wL6kwpW94rg

[solarman216]

Originally Posted by rayf3262

Ive seen some on eBay for under a fiver.

Ace will have a hunt round, Rick

[solarman216]

Found some at £77 for 12, ordered and paid, thanks Ray, Rick

[rayf3262]

Sounds good.
I would think you would also have the option of circulating the electrolyte from bottom to top with these pumps?

[solarman216]

Yes precisely my thoughts as opposed to bubbling air but need to be careful that debris is not stired up as well, will be looking at manufactures data as well, Rick

[macabethiel]

Originally Posted by Lazy-Ferret

Most fish tank don't spark, they use a pair of electrical coils, to pull a solenoid connected to a pair of bellows back and forward. Main problem is, the bellows tend to work harden, and you have to replace them every year or so.

What you ideally want is one of the old Medcalf Hy-Flo pumps, beautiful bit of kit, they use a coil to induce an eddy current into an aluminium disk, that then revolves, and drives 2 crank shafts connected to little pistons.... all you have to do is put a drip of oil on them once a month or so. Only problem is, they fetch quite good money now, as they are collectors items. I had 2 for my fish tanks, spent almost as much time watching the pumps, as watching the fish... Other thing is, rather than the annoying buzzing the modern ones make, these do a relaxing chuff...

I had one of the last Hy-Flo Pumps before they stopped production it was a double piston model it was mostly brass with a black plastic / ceramic cylinders. It was a work of art in itself watching the flywheel run. Sold it on e-bay about 10 years ago for more than it cost.